Orthodoxy, Truth, and Half-Belief

People who have a secular worldview often wonder how Orthodox Jews can believe what they do: for example, that the Torah is literally true, that God commanded all the mitzvot, or that the Creator of our vast universe chose our people as His own.
Secular people are especially puzzled by Modern Orthodox Jews, who simultaneously embrace science, modernity, and the Jewish tradition. How can they do it? Why do they do it?
The reasons aren't obvious, but they aren't irrational, either.
Reason #1: Half-Belief
The first reason is the phenomenon of "half-belief," discussed by philosopher H.H. Price in his book Belief:

"We quite often say of another person that he half-believes such-and-such a proposition though he does not wholly believe it."
A more accurate phrase might be that "... he does not always believe it." In the contexts where a half-belief is helpful, we believe it wholly. In other contexts, we don't believe it at all.

For example, I have a lucky tie. I wear it on important occasions, and because it's lucky, it gives me extra confidence. That extra confidence brings me good luck. When the occasion is over, I put the tie back in my closet and return to my usual belief that there's no such thing as luck.
Reason #2: Truth Depends on Context
The second reason is that truth is always relative to a particular description of the world and set of assumptions about it.
For example, does 1+1=2? Yes, certainly -- if you're using base 10. If you're using base 2, as computers do, then 1+1=10. By describing the number system differently, you change which statements in it are true or false.
Another example: Do the planets move in smooth elliptical orbits around the sun? Yes, certainly -- if you're using a Copernican-style model of the solar system. If you're using a Ptolemaic model -- which works but is a lot more complicated -- then the planets move in "epicycles" along their orbits around the earth.
The Jewish tradition gives one description of reality. Modern science gives a different description. What is true relative to one might not be true relative to the other. Judaism helps us find meaning and purpose in life. Science helps us understand and control physical reality. Beliefs that are useful in one context are not useful in the other, and vice versa.
But isn't science the only "correct" way of looking at the world? No. Both Judaism and science give pictures of the world that are incomplete, and each has its own purpose. They are not really inconsistent; only different.
Reason #3: Consequences Matter
The third reason is that belief can be justified by factors other than logic and empirical evidence. This idea is a "tough sell" because most people have a very simplistic notion of what belief is and what it does. But if you think about it for a moment, you realize that beliefs do a variety of things for us, apart from just making statements. They help us:
  • Predict physical or interpersonal events so we can plan correctly.
  • Announce our membership in groups, such as the Jewish people.
  • Comfort us in times of difficulty.
  • Strengthen us in times of challenge.
  • Express our loyalty and support.
Logic and evidence are relevant to the first item, but not to the others. When beliefs have different functions, they are justified in different ways. When beliefs have multiple functions, they're justified (or unjustified) in multiple ways, and then you must decide which way is the most important.
If you're building an airplane, you need beliefs from an engineering textbook instead of from the Jewish tradition. If you're trying to make a moral decision, you need beliefs from the Jewish tradition instead of from an engineering textbook. The purpose and results determine which belief set you use.
The Bottom Line
So that's it. First, we can half-believe things, so that we believe them in some contexts but not others. Second, what's true depends on how we describe the world. And third, how we describe the world depends on our purpose, which determines the beliefs that are helpful and good in a particular context.
That's why the Jewish tradition and modern science are both true and both helpful: each in its own context with its own purposes.